Generally, a liquid crystal display (LCD) device has problems related to a response speed since liquid crystal which configures a pixel of an LCD panel has a low response speed. For example, when an LCD is used in television, which displays moving pictures, an afterimage remains. Display controllers that control the LCD devices include a response time accelerator (RTA), which processes image data before a source driver which drives the LCD panel in order to resolve the problems related to the response speed. The response time accelerator compares data of a previous frame stored in an external memory with data of a current frame and outputs an acceleration value for accelerating data of the current frame.
As the resolution of the LCD device has recently increased, the amount of data of one frame has also greatly increased. Therefore, the capacity of the external memory included in the display controller for an operation of the response time accelerator has to also increase, and the operation speed has to be faster, and thus a high cost external memory is required. In order to resolve this problem, in the case of storing frame data, frame data is compressed and written to the external memory, and in the case of outputting frame data, data stored in the external memory is read and decompressed.